Variable resistors have been found widely useful in versatile mechanical instruments and electrical or electronic devices. Most commonly, the variable resistors are serving as adjusting and/or controlling elements for many kinds of signals, for example volume level of sound generating devices, light intensity of laminating means, temperature of heating apparatus, etc. The variable resistor also finds its usefulness in device calibration.
To meet the requirements for different devices or different purposes, heretofore, several kinds of variable resistors have been developed. These conventional variable resistors, although useful, possess certain disadvantages. For example, the most common disadvantage noted in the conventional variable resistor is that the conventional variable resistor is easy to be damaged when a user applies such a greater torque to rotate the shaft of a variable resistor that the rotatable member, of which the rotation is limited by stopper means, unexpectedly overlaps or breaks the stopper means and thus damaging the whole structure thereof.
Even if such an over-rotation does not damage the variable resistor directly, it also increases the abrasion and wear between parts of the variable resistor and thus shortening the duty life of the variable resistor.
Besides, such an over-rotation may also cause short circuit and thus deteriorating or totally destroying the function of the variable resistor.
Furthermore, the over-rotation may also result in a permanent deformation of the parts and eventually makes the variable resistor malfunction.
It is therefore desirable to have an improved variable resistor which overcomes the above-mentioned drawbacks.